Exploring the Physiological Effect of taVNS on Upper Limb Functional Rehabilitation

Transcutaneous auricular vagus nerve stimulation (taVNS), in addition to its application in treating specific disorders such as epilepsy, has shown promise in aiding the functional rehabilitation of the upper limb. Most patients with upper limb dysfunction have brain lesions and structural damage to brain networks. By conducting structural analysis of brain networks through electroencephalogram (EEG), we can investigate the effects of taVNS on the cortex directly from the source of the disease, offering a unique, bioelectrical perspective. To investigate the impact of taVNS on the neuromodulated upstream brain structures and to analyze the correlation between taVNS and the functional rehabilitation of the upper limbs, we proposed an analytical approach incorporating the network structure analysis. We conducted power spectra and phase lag index (PLI) calculations on experimentally collected EEG data and further analyzed network topology using graph theory. The results showed that compared with prestimulation, the relative power decreased in low frequencies and increased in high frequencies (
${p} < 0.05$
). In the alpha frequency band, the PLI showed an increasing trend (
${p}$
= 0.03), the minimum spanning tree (MST) analysis showed that the network topology became more integrated, and there were no regular changes observed in the control data (
${p} >$
0.05). In this work, we found that taVNS activates cortical motor areas and leads to stable changes in PLI and network structure in the alpha frequency band. The mechanisms through which taVNS modulates the power spectrum, alters connectivity, and enhances network structure integration in rehabilitation therapy have been revealed as having a positive impact on motor function recovery, providing valuable implications for the clinical application of taVNS in upper limb functional rehabilitation.